Weed eater engine conversion

First let me introduce myself, I've been following this thread for a couple months and just finished building my motor. I used a Craftsman 31cc weedwacker and kept the factory clutch.

The chain drive is #25 roller chain from surpluscenter.com. I experimented with 3:1 and 2:1 gear reduction, and found the 2:1 gave me much faster boat speed but still has plenty of torque to cut through weeds. I'm using a T-10 propeller.

My first exhaust was soldered together, which melted and I lost the muffler in the drink. I re-did the exhaust and brazed everything together. It's still not as quiet as I would like so I'm still doing some work on it.

Here's a youtube video I took this weekend.
http://www.youtube.com/watch?v=kItZqxFVLTU

 

That looks great! Thanks for sharing. You’ve basically created a hybrid long and short tail weed whacker motor! You get the gear reduction of a short tail and still have the long tails reach. How much does it weigh?

I’m starting to get back to my build since the lakes around my home are finally free of ice.

Erich

 

I'm pretty bad at guessing weight, but I'd say it's about 12 lbs.

 

see you mounted the chain drive behind the motor to keep the left hand rotation .... your torque multiplication is making the prop easier to rotate without stalling...lower revs more efficient ....personally the shaft looks a bit short but hey you might be very heavy in the back of that canoe .....

 

jryeo,
nice looking rig. where did u come up with the idea for running the shaft out in the open? does the shaft catch any weeds and get tangled up? from your pics it looks like u used brass bushing with grease zerts do the bushing heat up much with the limited amount of grease around them? what is the overall length and the shaft length? thanks for posting your project.

 

i've built a long tail with the 52cc engine and gear reduction i am running an 11 inch evans prop for a minn kota trolling motor. pushes me and a buddy in a 12x32 jon boat very well 500lbs plus the boat. very little change in speed from a little past 1/2 throttle on up i am gonna try a cavitation plate to help this.

 

Let's see some pics! What ratio of reduction are you running?

Erich

 

And...

How did you do the gear reduction? Would love to learn what you did and yes, pictures would be great. Please do share as many have tried different ways to get gear reduction and while some have worked, they are expensive options.

Mark

 

Im in the final stages of modifying a 4.5 meter bass boat hull (from my production molds) to an open boat with lots of space purely for fishing catfish and carp.

In the local dams all "hot" spots are out of reach for boats with normal outboard, let alone my cabin cruiser, since one must get through water densely populated with a water grass (looks like chop strand mat) that floats 4 inches just below the surface and wraps up an outboard propeller in a wink of an eye. My mate actually twisted his propeller shaft and snapped a prop on his Yammie trying to go through this grass...
Rowing is tough work since the boats rubs on the grass and one hardly make headway, let alone to go about 60 - 100 meter through that. After this the shallows lies with an abundance of monster catfish between the trees and no normal outboard can tread there as well due to lack of depth.

This made me follow this thread with interest because suddenly a longtail makes a lot of sense as on can lift the prop basically clean out of the water an just let the lower half of prop in water without the fear of seizing/damaging the motor as would have been the case of an outboard not getting cooling water in that state.

I have a brand new four stroke 5.5hp side shaft generator motor for the build and toyed with the idea of a drive shaft out in the open and see that JRYEO had the same idea and works quite well. Maybe I will go the shaft in tube route for simplicity.

Why do one need the oil or grease in tub? I was thinking of having a sealed bearing at the top (engine). At the prop a homemade affair from the lathe that will take a shaft seal, thrust bearing and again a shaft seal in that order from the prop in a water proof housing. In the lower and mid tube I will turn some grooved VESCONITE bushes that are self lubricating and have water circulating in the tube to cool the VESCONITE bushes instead of oil to lubricate bearings.
Since these four stroke engines turn at about 3500 - 4000 rpm (governed) the drive will be direct from engine shaft eliminating a reduction drive. The engine is a 160cc unit and I believe would be up to the task. The boat loaded will displace about 400kg

As soon as I start with the conversion I will post photos.

 

the reduction on mine is the scooter transmission. claims 5 to 1. let me figure out how to get pics off my blackberry its a unique design. by the way the cav plate helped alot.

 

here you go sorry its the only one so far. and yes its steel.

 

any body figured out how to wire the electric starter to charge a battery? at idle there is 11 volts wide open goes upwards of 20 volts. need a regulator/ rectifie r.but how to keep from engaging the starter and keep it connected to a battery? Diode? i know it will work just got to finger out the wiring.

 

Got it. You used the same 5:1 redcution that John O'Neal used awhile back. I think John was pushing an 11" prop or something close to it.

Thnaks for the info

Mark

 

Finally

I finally got my motor finished didn't try to reinvent the wheel just used a 52cc motor honda clutch plate, fashion up a drive tube with bushings and drive shaft. With some seals and a lock collar. Finally got everything wired except the electric starter along with the throttle cable. It worked fine in backyard lol. Will take to lake tommorrow can't wait to try it.

 

Hi all. I too have been following this post for a few months. I have a 32cc McCulloch off of a brush cutter. i am going to marry it to (whether it likes it or not) a honda 2hp lower unit. so far im $40 bucks in and countless hours of research. my question is as follows: Should or shouldn't i "lock" the perfectly good clutch that is on the motor? I have read stories within the pages of this post of melting plastic shrouds. I have also have seen plenty of designs like jryeo's sweet design that embraces the clutch. thank you for your time.